• The 10 highest-burden countries all exceed 32,000 STI cases per 100,000 people; South Africa tops the list at roughly 44,000.
• In the U.S. Mississippi has the highest STI risk score (57), while Vermont is the safest state with a score of 10.
• The worst-hit states have an STI risk score 5 times higher than the safest.

Summer travel comes with heightened health risks, as sexually transmitted disease rates spike during warmer months due to increased social activities and risky behaviors. LabCafe analyzed the riskiest destinations across the World and in the United States to help you stay safe this summer.

Where STIs are Most Concentrated

The map below shades each nation by its total STI rate per 100,000.

Countries with the Highest STI Rates (per 100,000 people)

1. South Africa: 43,984.8
2. Botswana: 41,231.2
3. Lesotho: 40,572.8
4. Malawi: 39,619.6
5. Eswatini: 39,003.5
6. Namibia: 35,178.9
7. Bermuda: 33,265.9
8. Brazil: 32,709.3
9. Gabon: 32,546.8
10. Zimbabwe: 32,379.5

Countries with the Lowest STI Rates (per 100,000 people)

1. Kazakhstan: 1,491.4
2. Pakistan: 8,051.9
3. Afghanistan: 8,722.4
4. Israel: 9,494.3
5. Nepal: 9,808.4
6. Bangladesh: 10,140.0
7. Yemen: 10,247.7
8. Bhutan: 10,939.5
9. Hungary: 11,045.7
10. United Kingdom: 11,076.2

Southern Africa’s concentration reflects entrenched epidemics of HIV and syphilis. Bermuda and Brazil show that tourism hubs and large urban populations can also drive rates upward. Conversely, many South-Central Asian nations exhibit low reported rates, though limited testing may mask true incidence.

U.S. Hotspots

Approximately 2.4 million combined STI cases are reported across the United States each year, though this number likely underrepresents the true burden due to undiagnosed cases. The CDC estimates that one in five Americans has an STI, with young adults aged 20-34 experiencing the highest infection rates

We calculated an STI-Risk Score for U.S. States, scaled from 0 to 100. This metric merges two pillars:

• STI Infection burden: county rates for chlamydia, gonorrhea, syphilis, and new HIV diagnoses.
• Socio-economic vulnerability: poverty, low education, lack of insurance, and vacant-housing share.

The national mean for the State risk score is approximately 29.3; scores above this threshold signal environments where travelers are more likely to encounter higher-than-average STI exposure or significant barriers to care. 

Top 10 States with the Highest STI Risk Score

1.     Mississippi (risk score = 57.0)
2.    Louisiana  (54.5)
3.    Georgia (48.0)
4.    Texas (45.0)
5.    Alabama (43.9)
6.    South Dakota (43.6)
7.    New Mexico (42.8)
8.    Arkansas (42.4)
9.    South Carolina (42.2)
10.    Nevada ( 41.9)

Bottom 10 States with the Lowest STI Risk Score

1.     Vermont (risk score = 10.1)
2.    New Hampshire (10.6)
3.    Maine (15.4)
4.    Utah (16.2)
5.    Minnesota (16.3)
6.    Idaho (16.8)
7.    Wyoming (17.8)
8.    Connecticut (18.1)
9.    Iowa (18.2)
10.    Massachusetts (18.7)

Our scoring shows that people in the Deep South face the nation’s greatest STI risk, Midwestern states follow behind them, and New England sits at the safest end. Overall, the worst-affected states score about five times higher on the risk scale than the least-affected ones.

Methodology

Data sources

• Global figures were taken from World Population that lists each country’s total reported STI rate (cases per 100,000 people) for 2021.
• U.S. figures came from the CDC’s 2023 STI  surveillance tables. Each line gives one pathogen-specific rate (chlamydia, gonorrhea, primary & secondary syphilis, or new HIV diagnoses) for a state or territory.
• Tourism demand International-arrival counts by U S city: International Trade Administration “U.S. States & Cities Visited by Overseas Travelers” .
• HealthTrackRx. (2024). STI Tests: Understanding Seasonality and Patterns.

Building the global ranking  

For each country, we kept the single total-STI rate, both sexes figure. We then ordered the full list from highest to lowest and recorded the ten highest-rate countries and the ten lowest-rate countries.

State risk score 

• Gather four pathogen rates per state(chlamydia, gonorrhea, primary + secondary syphilis, new HIV) and four ACS percentages (poverty, no-HS diploma, uninsured, vacant housing).
• Min-max scale each variable to 0–100 so the lowest county becomes 0 and the highest becomes 100.
• Infection burden = average of the four scaled pathogen measures.
   Socio-economic strain = average of the four scaled structural measures.
• Combine with a 2-to-1 weight:
   Risk=0.67×Burden+0.33×StrainRisk=0.67×Burden+0.33×Strain